Low fluid loss well-treating composition and method

ABSTRACT

A low loss well-treating composition comprising an aqueous mixture of solid wax or wax-polymer particles and a surfactant specifically selected for its ameliorating effect upon the low fluid loss properties of the solid particles, and a process employing this composition in well drilling and treating.

United States Patent Julius P. Gallns Anaheim, Cafit.

July 14, 1969 Aug. 24, 1971 Union Oil Company of Cafilornia Los Angelos,C1111. Continuation-impart of application Ser. No. 511,374, Dec. 3,1965, now Patent No. 3,455,390, dated July 15, 1969.

Inventor Appl. No. Filed Patented Assignee LOW FLUID LOSS WElL-TREATING[56] References Cited UNlTED STATES PATENTS 2,993,800 7/1961 Pickell106/271 3,108,441 10/1963 Watson 61/36 3,302,719 2/1967 Fischer 166/281X 3,316,965 5/1967 Watanabe 166/281 X 3,323,589 6/1967 Harvey 166/2743,354,180 11/1967 Ekissetal 106/271 X 3,370,650 2/1968 Watanabe 166/283X 3,431,976 3/1969 Harvey et a1... 166/274 3,455,390 7/1969 Gallus166/295 3,477,512 11/1969 Siegele 166/283 3,497,365 2/ 1970 Atherton eta] 106/271 Primary Examiner-Stephen J. Novosad Attorneys-Milton W. Lee,Richard C. Hartman, Lannas S.

Henderson, Robert E, Strauss and Dean Sandford LOW FLUID LOSSWELL-TREATING COMPOSITION AND METHOD This application is acontinuation-in-part of application Ser. No. 51 1,374, filed Dec. 3,1965, which matured into US Pat. No. 3,455,390, issued July 15,1969.

This invention relates to the treating of subterranean formationspenetrated by a well, and more particularly to methods for treatingpermeable subterranean formations employing a special low loss fluid. Inother aspects, the invention relates to improved low loss fluidcompositions useful in the treatment of oil and gas wells. The methodand compositions of this invention have particular application inhydraulic fracturing of subterranean formations, in well-treatingprocesses wherein a treating fluid is injected through a well and into aformation penetrated by the well, and to the completion of wells drilledinto oil-bearing producing permeable formations.

In various well-treating operations, such as for example, in thedrilling of wells into subterranean earth formations, in the completionof wells in permeable hydrocarbon-producing zones, and in stimulatingthe recovery of oil and gas from these producing zones, it is oftenadvantageous to inject a fluid into the well in such manner that thefluid is in contact with the earth formations penetrated by the well.Drilling muds, completion fluids, fracturing fluids, acids, and otherwelltreating liquids injected into the well bore preferentially flowinto zones of high permeability, called thief zones, not only resultingin loss and waste of the fluid, but also preventing the injected fluidfrom entering into zones of lower permeability in substantialquantities, or at least causing poor distribution between zones ofdifferent permeability. The loss of treating fluid to the formation isincreased at the elevated injection pressures employed in manywell-treating operations.

Fluid loss to permeable zones is particularly troublesome in hydraulicfracturing. conventionally, fracture planes or cleavages extending fromthe well bore into the formation are formed by subjecting the formationto elevated fluid pressure. Hydraulic pressure is developed by pumping afluid down the well and into contact with the underground formation tobe fractured. Since most formations are to some degree permeable, aportion of the injected fluid will pass from the well into theformation. The fracturing fluid must be injected into the well at avolume flow rate exceeding the rate of fluid loss into the formation in'order that the pressure exerted upon the formation by the fracturingfluid will be increased as the fluid is injected. Fluid injection mustbe continued in this manner until the pressure of the fluid at thefracturing zone is increased sufficiently to overcome the tensilestrength of the formation and the weight of the overburden, therebyeffecting an initial separation of the earth formation at a point ofminimum strength. Upon forming the initial fracture, fluid injection iscontinued to extend the fracture into the formation. Since the formationface contacted by the fracturing fluid is increased as the newly formedfractures are extended into the formation, fluid loss to the formationalso increases, particularly where additional permeable zones are openedby the fracture. Although higher fluid injection rates are required tofurther extend the fracture planes into the formation, fluidavailability is decreased because of increased loss to the formation.

Where one or more highly permeable zones are in communication with thewell and receiving the fracturing fluid, it is sometimes impractical toinject fluid at sufficiently high volume flow rates to effect thenecessary pressure buildup because of the large loss of fluid to thesepermeable zones. In other cases, fracturing can only be effected by theinjection of large quantities of fracturing fluid requiring a number ofinjection pumps. Such fracture jobs are expensive, not only because ofthe additional equipment required, but also because of the high energyconsumption in the useless injection of fluid into the formation. Moreimportantly, since the areal extent of the fracture plane is generallyincreased by higher volume injection rates into the actual fracture,loss of fluid to permeable zones of the formation results in lessfracturing fluid being available to extend the fracture. Thus, fluidloss is not only costly, but it can result in inferior-fracturing andultimately in decreased oil recovery.

Various techniques have beenproposed to reduce the loss of well-treatingfluids to the formation. For example, the penetration of treating fluidinto the formation can be decreased by adding thickening or gellingagents to alter the viscosity characteristic of the fluid. Napalm-typegelling agents are conventionally employed with hydrocarbon base fluids.Among the various substances which have been proposed as bodying agentsfor aqueous treating fluids are gums, such as guar, traganth, talha,damas, karaya, and ham; colloidal substances such as starch, dextrin,Irish moss and silica flour; and various water-soluble polymers such aspolyacrylates and polyacrylarnides. While bodied fluids are renderedless susceptible to fluid loss, high injection pressures are generallyrequired because of increased pressure drop through flow conduits.Particularly in the case of hydraulic fracturing, injection pressuresare often limited by the pressure rating of wellhead equipment, casingsand tubing strings. The increased pressure drop results in reducedhydraulic pressure in the fracturing zone. Further, on completion of thetreating job, the thickened fluid must be removed from oilproducingzones to restore permeability. Although gel-breaking fluids can beinjected for this purpose, destruction of the gel is only partiallycomplete resulting in some permanent loss of permeability.

Alternatively, it has been proposed to add to the treating fluidsubstances which do not have a pronounced effect on the properties ofthe fluid, but act instead to form a mat or deposit on the formationface, or which enter into the small flow channels or interstices of theformation rendering the formation more or less impermeable to thetreating fluid. Suggested materials include fibrous or finelydivided,substantially oil and water insoluble solid material capable ofsuspension in the treating fluid, such as shredded or granular particlesof asbestos, mica, plastic, cotton fibers, cellophane and chopped rope.Other materials employed as fluid loss additives include finely divided,insoluble minerals and salts. A well-known commercial fluid lossadditive employs a mixture of finely divided, relatively insolublesulfonate salt and alkaline earth metal carbonate, e.g., mixture ofcalcium sulfonate and calcium carbonate. However, everithrough theforegoing materials are more or less effective in'ibducing the loss offluid to the formation, they commonly have the, undesirable effect ofpermanently reducing the formation permeability, thus adverselyaffecting the ultimate recovery of oil from the producing zone.Similarly, less permanent fluid loss additives, such as particles of iceand asphalt emulsions, have not been generally satisfactory.

An improved method for treating permeable subterranean formations hasbeen disclosed in parent application Ser. No. 511,374, now US. Pat. No.3,455,390. In that method, small oil-soluble, water-insoluble wax orwax-polymer particles are dispersed in an aqueous treating fluid. Thedispersed solids are deposited in the formation during the well-treatingprocess so as to render the formation less permeable to the treatingfluid. The particulate matter is specifically selected to be slowlysoluble in the reservoir hydrocarbons. Thus, the matter deposited in theoil-producing zones during the treating process is dissolved or at leastsolubilized to the extent that they are removed from these zones by theformation hydrocarbons on return of the well to production, withsubstantially no permanent loss of formation permeability.

The discrete wax and wax-polymer particles are highly successful asdiverting agents and in many other well-treating applications, and tosome extent effect a reduction in the lossof fluid to the formation.However, in certain fracturing, welldrilling, completion andwell-treating operations, it is desirable to reduce the loss of fluid tothe formation to a value heretofore unobtainable with wax or wax-polymerparticles, yet without incorporating fluid loss control agents thatcause permanent permeability reduction, or which otherwise damage theformation.

Accordingly, it is an object of the present invention to provide animproved well-treating process for temporarily plugging a permeablesubterranean formation to prevent or retard the flow of fluidstherethrough. Another object is to provide a well-treating processemploying a low loss fluid composition which does not cause permanentloss of fonnation permeability. Another object is to provide an improvedmethod for hydraulically fracturing permeable formations. Still anotherobject is to provide a process for fracturing permeable formationswherein the loss of fracturing fluid to the formation is reduced. Afurther object is to provide a welltreating composition having theproperty of reduced fluid loss to the formation. A still further objectis to improve the fluid loss properties of aqueous dispersions of solidwax and waxpolymer particles. Other objects and advantages of theinvention will be apparent to those skilled in the art from thedescription thereof which follows The foregoing objects and theirattendant advantages can be realized with a low loss fluid comprising adispersion of oilsoluble, water-insoluble solid wax of wax-polymerparticles in an aqueous liquid containing a surface active agentselected for its ameliorating effect upon the fluid loss properties ofthe aqueous dispersion. These surface active agents, in combination withthe solid wax or wax-polymer particles, cooperate to reduce the fluidloss of the aqueous dispersion below that obtainable with the solid waxor wax-polymer particles alone, yet do not permanently affect thepermeability of the oil-bearing strata of the formation.

The oil-soluble, water-insoluble solid wax or wax-polymer particles aresolid particles of an oil-soluble petroleum wax, or homogeneous solidsolutions of petroleum wax and a polymer selected to exhibit acontrolled, slow solubility in the reservoir oil, and are insoluble inwater, acid and brine. Solid particulate matter exhibiting theseproperties can be dispersed in an aqueous carrier liquid without beingdissolved therein; thus, the solid agent retains its particulate formwhile dispersed in the aqueous liquid, and further, the properties ofthe aqueous medium are not altered by dissolution of the solid material.

n injection into the well, the dispersion tends to penetrate into theformation to a greater or lesser extent along all of the formation faceexposed to the fluid. The quantity of fluid entering into the formationand the depth of penetration is dependent in part on the porosity andpermeability of the structure. As the dispersion passes into theformation, some of the solids may be filtered from the carrier liquid soas to form a mat of solid particles on the face of the formation tendingto prevent further penetration of fluid into the fonnation. However, inmost zones having a more open structure, dispersed solids are carriedinto the formation with the carrier liquid to be deposited in the pores,and to therein form intersticial plugs preventing or retarding the flowof fluid into the formation. Since the dispersion has greater tendencyto enter into the more permeable zones, these zones will bepreferentially plugged so as to result in a partially plugged formationof more or less uniform permeability. The flow of fluid into theformation rapidly decreases as the plug is established, the totalquantity of fluid lost to the formation, being controlled, in part, bythe quantity of additive material employed. Thus, the loss of carrierfluid to the formation at the face of the well and along fracture facesextending into the formation is minimized by the combination of a mat ofsolid particles formed on the formation face and by intersticialplugging within the formation.

It is desired that the oil solubility of the wax or wax-polymerparticles be such that upon their placement in the formation, or uponthe face of the formation, they will remain as solids for a time periodsufficient to perform a particular well operation, but will be slowlydissolved in the oil, or at least solubilized to the extent that theyare removed from the oil-producing zones on return of the well toproduction. Thus, the wax or wax-polymer particles function as pluggingagents effective in reducing the permeability of the formation for alimited time period, such as from a few hours to several days, dependingupon the solubility or dispersibility of the particles in the reservoiroil. Further, since the particles are substantially insoluble in connatewater and brine, plugs established in waterproducing zones, in which oilis not present to function as a solvent, will be largely permanentresulting in selective water shutoff.

The solid oil-soluble, water-insoluble plugging agents that can be usedin the practice of this invention can be solid particles of petroleumwax, such as crystalline and microcrystalline paraffin waxes meltingbetween about 130 F. and about 165 F. The wax component is selected forits solubility in the reservoir oil, and preferably has a melting pointabove the injection temperature, and more preferably above the reservoirtemperature, although in some treating applications, sufficient coolingis obtained by the injection of the aqueous fluid to permit the use ofsolid particles comprised of waxes melting somewhat below the reservoirtemperature.

A superior fluid loss additive for dispersion in an aqueous carrierliquid can be formed from particulated homogeneous solid solutions ofwax and (1) an addition polymer of an olefin having between 2 and 4carbon atoms, (2) copolymers of an olefin having between 2 and 4 carbonatoms and an alkyl acrylate containing not more than 4 carbon atoms inthe alkyl group, (3) copolymers of an olefin having between 2 and 4carbon atoms and an ester formed by the reaction of butenic acid and analcohol having no more than 4 carbon atoms, and (4) copolymers ofolefins having between 2 and 4 carbon atoms and an ester formed by thereaction of acetic acid and an unsaturated alcohol having no more than 4carbon atoms.

Preferred polymer component materials include polyethylene,polypropylene, polybutylene, copolymers of ethylene and vinyl acetate,copolymers of ethylene and methyl methacrylate, and copolymers ofethylene and ethylacrylate.

- A single polymer component selected from the above classes ofpolymeric components may be employed, or two or more such material canbe combined. Each of the aforesaid polymer components will impartsomewhat different properties of strength, ductility, solubility,melting point, density, and dispersibility to the final solidcomposition. Desired properties not obtainable with a single polymericmaterial can often be achieved with blends of two or more of thesepolymers, or by the addition of other polymers and resins to thecomposition.

A number of wax-polymer particle compositions and methods of producingthese particles are disclosed in US. Pat. Nos. 3,302,719 and 3,316,965.I

The solid wax and wax-polymer particles used in the practice of thisinvention vary widely in size and shape. Typically, these particles canbe spheroids, cubes, granules, buttons, flat disks, or mixtures thereof,having mean diameters in the range of from about one-half inch to about1 micron and less. More particularly, the particles can be cubes,buttons or disks having a size in the range of from about one-quarterinch to about one-half inch, spheroids or granules in the size range offrom about 4 to 200 mesh U.S. sieve, or particles having a mean diameterfrom about 1 to about 50 microns.

The particular solid particle content required usually depends upon thecharacteristics of the formation and the degree of fluid shutoffdesired, with additive contents within the range of about 0.1 to about60 weight percent being generally satisfactory in most operations. Inhydraulic fracturing, where a fairly high degree of fluid shutoff isdesirable, additive contents above about 10 weight percent, andpreferably within the range of about 10 to 40 weight percent arepreferred. in other treating applications, such as for example inacidizing, where only partial plugging to effect more uniformdistribution of the injected fluid throughout zones of varyingpermeability is desired, lower additive contents are preferred, andparticularly additive contents of less than 10 weight percent.

The fluid loss properties of aqueous fluids containing theabove-described oil-soluble, water-insoluble wax or waxpolymer particlesare substantially enhanced by incorporating therein a selected surfaceactive agent that sy nergistically cooperates with the dispersed solidparticles to reduce fluid loss. It is well known that most surfaceactive agents improve the dispersibility of water-repelling(hydrophobic) particles in aqueous liquids. However, surface activeagents that provide good dispersibility do not necessarily provide goodfluid loss properties, and in fact, some surfactants which produce asuperior particle dispersion may have relatively little effect on fluidloss.

Surface active agents that synergistically cooperate with the solid waxor wax-polymer particles are nonionic surface active ethers, polyethersand thioethers having an HLB factor between about 8.5 and 19.5, nonionicsurface active esters having an HLB factor between about and 14.5nonionic surface active amides having an HLB factor between about 7 and10.5, nonionic surface amines having an HLB factor between about 4 and10, anionic surface active sulfonates having an AFL factor between about7 and 12.5, anionic surface active organo-sulfates having an AFL factorbetween about 5.5 and 7.5, anionic surface active organo-phosphateshaving an AFL factor between about 12 and 39, and cationic surfactantshaving a CF L factor between about 19 and 38.

The term HLB factor" stands for hydrophile-lipophile balance, and is ameasure of the hydrophilic (waterloving) and lipophilic (oil-loving)nature of a surfactant. The HLB factor has an arbitrary scale of 0 to20, with a value of 0 representing a completely lipophilic substancee.g. oil, and a value of 20 representing a completely hydrophilicsubstance, e.g. water. The HLB factor for a particular surfactant can beobtained experimentally by conventional means, although such methods areoften arduous and time consuming. An approximate HLB factor can bepredicted from the molecular structure of the surfactant in accordancewith the following relationship:

. HLB=(H/H+L) 20 wherein H is the molecular weight of the hydrophilicpart of themolecule; and

L is the molecular weight of the lipophilic part of the molecule.

The term AFL factor stands for anionic fluid loss factor, and is aparameter basedon the chemical composition of the surfactant and itsresulting ions in accordance with the following relationship:

wherein C, total number of carbon atoms in the anionic portion of themolecule;

O total number of oxygen atoms in the entire molecule;

N, total number of nitrogen atoms in the entire molecule;

C total number of carbon atoms in the cationic portion of the molecule;

S total number of sulfur atoms in the entire molecule;

B, total number of benzene rings in the entire molecule;

and

1 total number of anions formed on the complete ionization of themolecule.

The term CFL factor stands for cationic fluid loss factor and is aparameter based on the chemical composition of the surfactant and itresulting anions in accordance with the following relationship:

wherein C total number of carbon atoms in they cationic portion of themolecule;

0, total number of oxygen atoms in the entire molecule;

N, total number of nitrogen atoms in the entire molecule;

S, total number of sulfur atoms in the entire molecule; C, total numberof carbon atoms present in the anionic portion of the molecule;

total number of halogen atoms in the entire molecule; and I total numberof cations formed on the complete ionization of the molecule.

Nonionic surface active agents that syner'gistically cooperate with thesolid wax and wax-polymer particles in aqueous solution to provide a lowloss fluid are e'thers, polyethers, and thioethers having HLB factorsbetween about 8.5 and 19.5, and preferably between about 13 and 19,characterized by the following generalized formulas esters having HLBfactors between about 10 and 14.5, and I preferably between about 11.5and 14, characterized by the following generalized formula and amineshaving HLB factors between about 4 and 10, preferably between about 4.5and 9, characterized the following formulas wherein R is a lipophilicorganic group containing from about 6 to about 35 carbon atoms,exemplary of which are alkyl groups, such as hexyl, heptyl, octyl,nonyl, decyl, hendecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,hexadecyl, heptadecyl, octadecyl, nonadecyl, etc.; animal fats,vegetable 011 and fatty acid derivatives, such as derivatives of linseedoil, soybean oil, tung oil, palm oil, coconut oil, whale oil, peanutoil, olive oil, cottonseed oil, tail oil, etc.; alkylaryl groups such ashexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl,alkenyl, cycloalkyl, alkynaphthyl, anthryl and alkylanthryl groups; androsin compounds; and wherein R is a hydrophilic organic group containingfrom about 1 to 4 carbon atoms, exemplary of which are carboxy and alkylderivatives thereof, such as carboxymethyl, carboxyethyl, etc.; amidoandalkyl derivatives thereof, such as amidomethyl,

amidoethyl, etc.; aminoalkyls, such as aminomethyl, aminoethyl,aminoprophyl, etc.; hydroxyalkyls, such as hydroxymethyl, hydroxyethyl,hydroxypropyl, hydroxyisopropyl, etc.; alkoxy and imidoalkyl groups; andpolyfunctional organic groups such as polyethers, polyesters, polyhydricalcohols and polyamines containing from about 4 to about 200 carbonatoms where each functional group is separated by 1, 2 or 3 carbonatoms; and wherein a and c are integers having a value of from about 3to 50, and b is an integer having a value of from about 5 to 80.

Anionic surface active agents that synergistically cooperate with thesolid wax and wax-polymer particles in aqueous solution to reduce fluidloss are sulfonates having an AFL factor between about 6 and 12.5, andpreferably between about 6.5 and 10.5, characterized by the followinggeneralized formula mso n organo-sulfates having an AFL factor betweenabout and 9, and preferably between about 5.5 and 7.5, characterized bythe following generalized formula prism-R organo-phosphates having anAFL factor between about 12 and 39, and preferably between about l5 and32, characterized by the following generalized formulas 2 MI PO4Rg, andIIPO;

wherein M is a cation, exemplary of which are alkali metals, such assodium, potassium and lithium; ammonium and substituted ammonium groupssuch as triethanol amine and tiiethylainine; and hydrogen; and wherein Ris a lipophilic organic group containing up to 200 carbon atoms, wdusually containing from about 6 to 100 carbon atoms, and which may alsocontain some hydrophilic functional groups, exemplary of which arealkyl, aryl, alkylaryl, alkenyl, alkenylaryl, alkylamine,alkylpolyarnine, alkylester, alkylpolyester, alkylether, alkylpolyether,alkylarylpolyether, cycloalkyl, naphyl, alkylmercaptyl, anthryl andalkylanthryl groups; and animal fat, vegetable oil, fatty acid and rosinderivatives.

Cationic surface active agents that synergistically cooperated with thesolid wax and wax-polymer particles in aqueous solution to provide a lowloss fluid are substituted ammonium compounds, alkyl-substitutedoxazolines, substituted imiduolines, rosin-amines, etc., having CFLfactors between about 19 and 38, and preferably between about 22 and 35,some of which are characterized by the following generalized formulasmumm [mammallRzla h gn teswherein X is an anionic group, exemplary ofwhich are halogens such as chloride, bromide, fluoride, iodide, etc.;organic groups such as formate, acetate, propionate, butyrate,isobutyrate, and benzoate; and wherein R, R, and R are organic groups asdefined supra.

Exemplary of the surface active agents that can be employed in thepractice of this invention are the commercial surfactants listed intable 1.

Surface-active materials that are particularly preferred agents for usewith aqueous dispersions of solid wax and waxpolymer particles to reducefluid loss are (l) a condensation product of lauric or coconut fattyacid and diethanolamine, exemplary of which are surfactants marketed bythe Onyx Chemical Company under the trademark Onyx WW and by the StepanChemical Company under the trademark Ninol 737 and Ninol l28l; (2) anoctylphenoxy polyethoxy ethanol having a polyothoxy chain containingbetween about l5 and 35 mole equivalents of ethylene oxide, exemplary ofwhich are surfactants marketed by the Rohm and Haas Company under thetrademarks Triton 165 and Triton 305; (3) a condensation product ofstearamine or cocoamine and between about 2 and 4 mole equivalents ofethylene oxide, exemplary of which are surfactants marketed by ArmourIndustrial Chemicals Company under trademarks Ethomeen CH2 and Ethomeen18/ l 2; (4) a condensation product of coconut fatty acids and betweenabout 4 and 6 mole equivalents of ethylene oxide, exemplary of which isa surfactant marketed by the Armour industrial Chemical Company underthe trademark Ethofat C/ 15; and (5) dilauryldimethyl ammonium chloride,exemplary of which is a surfactant marketed by the Armour IndustrialChemical Company under the trademark Arquad 2075.

While the foregoing surface-active agents in combination with aqueousdispersions of wax and wax-polymer particles cooperate to efiectivelyreduce fluid loss below that obtained with either an aqueous solution ofthe surface active agent or an aqueous dispersion of solid wax orwax-polymer particles individually, it is recognized that othersurface-active materials may also produce this synergistic effect. Arelatively simple screening test to determine the effectiveness of asurface-active material can be performed by admixing a measured amountof the surfactant, 5 grams of solid wax or wax-polymer particles, and500 milliliters of water. One face of a kerosenesaturated cylindricalBerea sandstone test core having a length and a diameter of 1 inch iscontacted with the dispersion at a pressure of 500 p.s.i.g., with theother face of the test core being maintained at atmospheric pressure.Fluid exiting from the core is collected and the cumulative volume ofcombined fluid effluent collected over a 5 minute period measured, Therelative fluid loss reduction is determined by comparison of themeasured fluid loss with the fluid loss obtained with a surcles.

Although a number of surface active agents may synergistically cooperatewith the wax or wax-polymer particles to provide somewhat lower fluidloss than obtained with either the aqueous surfactant solution or theaqueous dispersion of wax or wax-polymer particles individually, onlythose surface-active agents that reduce the fluid loss to approximatelyone-half of that obtained with the surfactant-free dispersion of solidwax of solid wax and wax-polymer particles are preferred, and the morepreferred surface-active agents are those that reduce fluid loss toapproximately one-third of this value.

TABLE 1.-EXEMPLARY COMMERCIAL S URFACTANTS Approximate characteriza-Company Trademark Surfactant; type tion factor Rohm and 1Iaas TritonX-35. Nonionic ether 1. IILB 8 8 D0. Triton X-i5. (lo llLB 11.2 D0Triton X-165. HLB 15.9 D0 Triton X-305. HLB 17.4 Retzloti Chem. Co.Retzoual NP HLB 13.8 Armour Ind. Chem.. Ethofat 0/15 HLB 10.1 Do EtholntC/15 HLB 12.4 Atlas Chem. Inc.. Span Z0 HLB 11.8 Do Tween 85. HLB 11.2Armour Ind. Chem. Ethomid 0/15.. HLB 10.5 Onyx Chem. Corp Onyxol WW;I-ILB 9.2 Stepan Chem. Co Ninol 1281 HLB 8.8 0 l Ninol 737 1 1 1 "dollLB 0.0 Armour Ind. Chem... Ethomeen 0/12 Nonionic aminc HLB 7.3 Do.EthomeeriT/l5 d0 HLBQJ Mona Ind Monawet -70 Anionic sulfonatc AFL 12 E.I. (111 lontde Nemours... DupunolC d0 AFL? General An'ilinv and Film.Gaiac PIE-510 Anionic phosphate AFL 36 T) Gal'uc MC 470. (l0

. Nalquot G813. Nalquot (TH/-13... Arquad JG-75" Arquad 2HT Theconcentration of surface active agents employed in the low loss fluidsof this invention can vary over a wide range depending upon thedispersibility of the surfactant in the aqueous fluid, and the amount ofsolid wax or wax-polymer particles dispersed in the fluid. Generally,however, the concentration ranges from about 0.05 to 25 weight percentof surfactant based upon the weight of wax particles, i.e., from about0.0005 to 0.25 part by weight of surfactant per unit weight of solidparticles. A more preferred range of surfactant concentration is betweenabout 0.1 and 15 weight percent of surfactaut based upon the weight ofthe solid wax and wax-polymer particles. It is also preferred that thesurfactant concentration increase with decreasing particle size, i.e.,as the surface area of the solid particles increases, it is preferredthat the surfactant concentration be increased proportionally.

The surfactant and the particulate additive can be admixed with theaqueous carrier liquid at the well site, or alternatively, aconcentrated slurry of the solid particles and the surfactant can beprepared and mixed into the carrier liquid. In cases where it isdifficult to disperse the surface-active agent in the aqueous liquid, itmay be necessary to first heat the carrier liquid to disperse thesurfactant prior to adding the solid particles.

The low loss fluid composition of this invention can be effectivelyemployed as a drilling fluid in well drilling, and particularly as acompletion fluid in the drilling of oil and gas wells. In thisapplication, the fluid is circulated from the surface to the drillingzone in a subterranean formation during the drilling operation, and atleast a portion of the fluid is returned to the surface. Thecompositions of this invention also have utility as fracturing fluids inthe hydraulic fracturing of oil wells, the fracturing fluids beinginjected under elevated pressure to cause fracturing of the subsurfaceformation, and in chemical treating, acidizing, and other well-treatingoperations wherein it is desired to control fluid loss to permeableunderground structures.

The invention is further illustrated by the following examples which areillustrative of specific modes of practicing the invention and are notintended as limiting the scope of the invention as defined by theappended claims.

EXAMPLE 1 l Co n- L- NR Niolecular weight of hydrophilic portion:

Oxygen 7X16 =112 Carbon 11 X 12 132 Hydrogen 21 X 1 =21 Molecular weight265 Molecular weight of lipophilic portion:

Carbon 18X12 =216 Hydrogen 37 1 =37 Molecular weight 253 The AFL factorfor the anionic surfactants is calculated as follows: Exemplarysurfactant:

HAFL=11 The CFL factor for the cationic surfactant is calculated asfollows: Exemplary surfactant: [(C, H N(CH Cl CFL=35 EXAMPLES 2-51 Theeffectiveness of various surfactants in improving the fluid lossproperties of solid wax-polymer particles is demonstrated by a series offluid loss tests. In each test, a standard test core is contacted understandard conditions of temperature and pressure with an aqueous fluiddispersion containing the same proportion of solid wax-polymer particleand the same surfactant concerm'ation, and the volume of fluid passingthrough the core is measured. A different surfactant is employed in eachof the tests, and the volume of fluid passing through the cores in afixed time period is indicative of the fluid loss properties of thevarious dispersions.

The aqueous dispersions are prepared by admixing 5 grams of wax-polymerparticles having a mean diameter less than 50 microns with 500milliliters of water and 0.25 gram of surfactant. The particles employedin this example are homogeneous solid solutions of weight percentparaff'm wax having a melting point of F. and 10 weight percentethyleneethylacrylate copolymer marketed by the Dow Chemical Companyunder the trademark Zetafax 1075. It is sometimes necessary to firstdisperse the surfactant in the water prior to the addition of thehydrocarbon-polymer particles, and may require heating the initialaqueous solution to dissolve the surfactant. The dispersion is stirredat high speed for 5 minutes prior to being transferred to the test coreapparatus, and is also stirred throughout the fluid loss test.

The test cores are cylinders of Berea sandstone, 1 inch in diameter by]inch in length. The cores are mounted in standard brass core holders sothat one flat end face of the cylinder can be contacted with the aqueousdispersion under 500 p.s.i.g. pressure, with the other face of thecylinder being amaintained at atmospheric pressure. Thus, the test coreis sub- The cumulative volume of combined fluid effluent collected overa 5 minute period is measured and reported in table 3. An approximatesurfactant characterization factor is also indicated for eachoflthesurfactants.

The cumulative fluidlo ss ofmqueous dispersiohs tesfed in examples 2-51are illustrated in the drawings, of which:

FIG. 1 is a plot of the eminent/annulus for the aqueous dispersionscontaining various nonionic surface-active ethers tested in examples 2-8as a function of the HLB factor of the surfactant;

FIG. 2 is a plot of the cumulative fluid loss for the aqueousdispersions containing various nonionic surface-active esters tested inexamples 9-14 as a function of the I'ILB factor of the surfactant;

FIG. 3 is a plot of the cumulative fluid loss for the aqueousdispersions containing various nonionic surface-active amides tested inexamples 15-19 as a function of the I'ILB factor of the surfactant;

FIG. 4 is a plot of the cumulative fluid loss for the aqueousdispersions containing various nonionic surface-active amines tested inexamples 20-26 as a function of the I-ILB factor of the surfactant;

FIG. 5 is a plot of the cumulative fluid loss for the aqueousdispersions containing various anionic surface active sul- TABLE2.FLL'1I) LOSS THROUGH PERMEABLE CORES Characterization Surfactantfactors Approximate Fluid loss Example Company Trade name Chemical HLBAFL CFL (ml./ min.)

NONIONIC ETHE RS 2 Wyandotte Chem. Corp Pluronio L/62 Polyoxyethylene,polyoxy- 4 215 propylene. 3 do Pluronic L/64 do 8 170 4 v Rohm and HaasTriton X-35 Octylphenoxy, polyoxy- 8.8 135 ethylene ethanol. Triton 130do.. ..TritonX-l65. do 35 7 do Triton X-305... ....do 52 s e. RetzlofiChem Retzonal NP-lOO Alkylphenoxy, polyoxy- 125 I ethylene ethanol.

NONIONIC ESTERS I 9 Armour 1nd. Chem Ethofat 0/15 Polyt iethoxylatedfatty acids"... 175 o 76 Sorbitan monolaurate. 160 9 i f l9l p i l li. wi Tween 85. Polyoxyethylene sorbitan tri- 120 oleate. 14 Methyl laurate300 NONIONIC AMIDES l5.. Armour Ind. Chem Ethomid 0/15 Polyethoxylated10.5 180 16.. Om s Chem Corp. Onyxol WW Fatty acid amides. 9. 2 57 17..Stepau Chem Co \in0l1281... 0... 8.8 19 18 o Nlu01737.. d0 9.0 l9 vStearamide 4. 8 300 NONIONIC AMINES Ethomoen C/12 Polyethoxylated amines57 Ethomeen C/15... do 170 Ethomeen 18/60.. .do. 300 Ethomeen 18/20. .do280 Ethomeen T/15..- ..do 110 Ethomeen 18/12 do 26 Octadecylamine 300ANIONIC SULFONATES 27 General Aniline & Film Corp Igepou AC-78 Coconutoil acid, esters of 9 65 sodium isethionate. 28 .d0 Igepon TN-74SodiumtN-methyl-N-palmitoyl 13 175 taura e. 29 ..d0 Igepon TE-42. SodiumN-methyl-N-tallow acid taurate. 30 American Cyanam1d Aerosol OTDioctylester sodium sulfosuccinic acid. 31 Mona Ind. Inc. Monawet DC-7odo 32 C Chem.. Ornite No. S Alkylaryl sodium sulfonate. 33 Monsanto Co.Santonerse D. do

34 Propylbenzene sodium sul- Mum; MM fonate. v w

ANIONIC SULFATES 35 E. I. du Pout de Nemours & Co- Dupanol C .1. Sodiumlauryl sulfate 150 36 ..d0 Dupanol L-144 Sodium alkylaryl sulfate 210 37Sodium propyl benzene sulfate 300 ANIONIC PHOSPHATES 38 Ge eral Aniline& Film Corp..... Game PE-510 Free acid of a complex organic 36 135phosphate ester. 39 ..d0 Gafao RE-610 "do 42 130 .(10 Gafac MC-470Sodium salt ofa complex organic 20 72 phosphate ester.

(11') 1 NaOP(OC H 4 30 II 4 .0..." .L NUOP(OC25H53)2 300 ANIONICMISCELLANEOUS 3 Tall oil soap 16 230 44 HQYCUI S Int: Dresinate 731Sodium soap of a modified rosin 16 300 CATIONIC SURFACTANTS 45 NnlcoChem Nalquot G8-13 Alkylimidazoline derivative 24 93 46. do NalquotG9-13 do l!) 160 47 Armour Ind. Chem Armao C Acetic acid salts of then-alkyl 5 3 amines. Arquad 18-50 Quaternary ammonium chlorides 17 200Arquad 20-75 do 25 64 Arquad ll-IT do 35 51 300 [(C1 H 1) NH] Cl fonatestested in examples 27-34 as a fun ction of the AFL factor of thesurfactant;

P10. 6 is a plot of the cumulativefluidloss for the aqueous dispersionscontaining various anionic surface active organosulfates tested inexamples 35-37 as a function of the AFL factor of the surfactant;

FIG. 7 is a plot of the cumulative fluid loss for the aqueousdispersions containing various anionic surface active organophosphatestested in examples 38-42 as a function of the AF L factor of thesurfactant; and

FIG. 8 is a plot of the cumulative fluid loss for the aqueousdispersions containing various cationic surfactants tested in Examples45-51 as a function of the CFL factor of the surfactant.

EXAMPLE 52 This example demonstrates the superiority of certainsurfactants in improving the fluid loss properties of aqueousdispersions of solid hydrocarbonpolymer particles as compared with othersurfactants having similar particle-dispersing capabilities.

Two aqueous dispersions are prepared by measuring the volume of 5 gramsof the hydrocarbon-polymer particles employed in examples 2-51 andadmixing these particles in 500 milliliters of water containing 0.25gram of surfactant. One dispersion is prepared with a surface-activealkylphenoxypolyoxyethylene ethanol marketed by the Retzloff ChemicalCompany under the trademark Retzanol NP-100, and the other dispersion isprepared with a surface-active fatty acid amide marketed by the OnyxChemical Company under the trademark Onyxol WW. The dispersions arestirred for 2 minutes and then allowed to remain quiescent for 2minutes. At the end of the quiescent period the volume of the particlessettled from the solution is measured and the percentage of particlesremaining calculated. The dispersions are again stirred and theircumulative fluid loss is determined in accordance with the method ofexamples 2-5 1. It is observed that the fluid loss with the dispersioncontaining the surface-active fatty acid amide is less than one-half ofthat obtained with the dispersion employing the alkylphenoxyethyleneethanol, even though both dispersions have the same dispersibility. Theresults of these tests are reported in table 3.

TABLE 3 Cululative Fluid Loss (mL/S ruin.)

Dispersion,

Surfactant Vol. I;

EXAMPLE 5:?

A method for fracturing a subterranean oil-bearing formation employingthe aqueous low loss fluid compositions of this invention is illustratedin this example. A well is drilled through the formation and cased to adepth below the producing zone with 7-inch steel casing. The casing isperforated with four I i/8 inch perforations per foot between theinterval of 6,873 feet and 6,880 feet Tubing is run into the well to adepth of 6,870 feet and a packer installed immediately above theterminus ofthe tubing.

The fracturing fluid is prepared by admixing 0.24 lbs. of asurface-active fatty acid amide marketed by the Onyx Chemical Companyunder the trademark Onyxol WW and 2.5 pounds of wax-polymer particlesper gallon of fracturing fluid. The wax-polymer particles are homogenoussolid solutions comprised of percent paraffin wax melting between about75 F. and 142 F. and 10 percent ethylene-vinyl acetate copolymermarketed by the E. l. DuPont Chemical Company under the trademark Elvax.Approximately 50 percent of the EXAMPLE 54 This example demonstrates thesynergism between one of the preferred surfactants and the solidwax-polymer particles in ameliorating the fluid loss of an aqueousdispersion of the solid particles.

Four test fluids are prepared and their corresponding fluid 4 propertiesmeasured in accordance with the method employed in examples 2-51. Thefirst test fluid comprises 500 milliliters of water. The second fluidcomprises a mixture of 500 milliliters of water of 0.25 gram of asurface-active fatty acid amide marketed by the Onyx Chemical Companyunder the trademark Onyxol WW. The third test fluid comprises an aqueousdispersion of 5 grams of the solid wax-polymer particles employed inexamples 2-51 in 500 milliliters of water. The fourth test fluidcomprises an aqueous dispersion of 5 grams of wax-polymer particles in500 milliliters of water containing 0.25 gram of Onyxol WW.

It is observed that the fluid loss of ambient water is decreased by 5percent with the addition of a surface-active fatty acid amide to thewater and by 27 percent with the addition of hydrocarbon-polymerparticles, while a decrease of 86 percent occurs with the addition ofboth the fatty acid amide and hydrocarbon-polymer particles. The resultsof these tests are reported in table 4.

TABLE 4 Test Fluid Loss Fluid Composition (rnl.l$ min.)

1 Water 410 2 Water Surfactant 390 3 Water Particles 300 4 WaterParticles Surfactant 57 While particular embodiments of the inventionhave been described, it will be understood, of course, that theinvention is not limited thereto since many modifications can be made,and it is intended to include within the invention any suchmodifications as fall within the scope of the claims.

The invention having thus been described, 1 claim:

1. A method of treating a permeable subterranean forma tion penetratedby a well which comprises injecting into the well a dispersioncomprising from 0.1 to 60 weight percent of oil-soluble,water-insoluble, homogeneous solid particles comprised of petroleum waxin an aqueous liquid containing a surfactant in an amount of from about0.0005 to 0.25 parts per part of solid particles and selected from thegroup consisting of nonionic surface-active ethers and thioethers havingan HLB factor between about 8.5 and 19.5, nonionic surface-active estershaving a HLB factor between about 10 and 14.5, surface-active amideshaving an HLB factorbetween about 7 and 10.5, nonionic surface-activeamines having an HLB factor between about 4 and 10, anionicsurface-active sulfonates having an AFL factor between about 7 and 12.5,anionic surface-active organo-sulfates having an AFL factor betweenabout 5.5 and 7.5, anionic surface-active organo-phosphates having anAFL factor between about 12 and 39, cationic surface active agentshaving a CFL factor between about 19 and 38.

2. The method defined in claim 1 wherein said oil-soluble,water-insoluble solid particles are comprised of a solid solution ofpetroleum wax and polymer.

3. The method defined in claim 2 wherein said polymer is selected fromthe group consisting of 1) addition polymers of an olefin having between2 and 4 carbon atoms, (2) copolymers of an olefin having between 2 and 4carbon atoms and an allryl acrylate containing not more than 4 carbonatoms in the alkyl group, 3) copolymers of an olefin having between 2and 4 carbon atoms and an ester formed by the reaction of butenic acidand an alcohol having no more than 4 carbon atoms, and (4) copolymers ofolefins having between 2 and 4 carbon atoms and an ester formed by thereaction of acetic acid and an unsaturated alcohol having no more than 4carbon atoms.

4. The method defined in claim 2 wherein said polymer is selected fromthe group consisting of polyethylene, polypropylene, copolymer ethyleneand methyl methacrylate, copolymer ethylene and vinyl acetate, andcopolymer ethylene and ethyl acrylate.

5. The method defined in claim 2 wherein said petroleum wax is aparaffin wax.

6. The method defined in claim 1 wherein said aqueous liquid is selectedfrom the group consisting of 1) water, (2) brine, (3) aqueous acidsolutions, and (4) aqueous caustic solutions.

7. The method defined in claim I wherein said surfactant is (l) acondensation product of lauric or coconut fatty acids anddiethanolamine, (a) an octlyphenoxy polyethoxy ethanol having apolyethoxy chain containing between about 15 and 35 mole equivalents ofethylene oxide, (3) a condensation product of stearamine of cocoamineand between about 2 and 4 mole equivalents of ethylene oxide, (4) acondensation product of coconut fatty acids and between about 4 and 6mole equivalents of ethylene oxide, or dilauryldimethyl ammoniumchloride.

8. A method of completing a well drilled into a permeable subterraneanformation which comprises circulating a low loss fluid from theformation surface to the drilling zone in said formation during thedrilling operation and returning to the surface at least a portion ofsaid fluid, said low loss fluid comprising a dispersion of oil-soluble,water-insoluble homogeneous solid particles comprised of petroleum waxin an aqueous liquid containing a surfactant selected from table 1.

9. The method defined in claim 8 wherein said solid particles arecomprised of a solid solution of petroleum wax and polymer.

E0. The method defined in claim 9 wherein said surfactant is (l) acondensation product of lauric acid or coconut fatty acids anddiethanolamine, (2) an octylphenoxy polyethoxy ethanol having apolyethoxy chain containing between about and 35 mole equivalents ofethylene oxide, (3) a condensation product of stearamine or cocoamineand between about 2' and 4 mole equivalents of ethylene oxide, (4) acondensation product of coconut fatty acids and between about Hers moleequivalents of ethylene oxide, or ammonium chloride.

ii. A method of fracturing a permeable subterranean formation penetratedby a well which comprises injecting a low loss fluid into said well andinto contact with said formation at a pressure and volume flow ratesufircient to fracture said formation, said low loss fluid comprising adispersion of oil-soluble, water insoluble, homogeneous solid particlescomprised of petroleum wax in an aqueous liquid containing a surfactantselected from table 1.

H2. The method defined in claim 11 wherein said solid particles arecomprised of a solid solution of petroleum wax and polymer.

13. The method defined in claim 11 wherein said surfactant is (1) acondensation product of lauric acid or coconut fatty (5 dilauryldimethylacids and diethanolamine, (2) an octylphenoxy polyethoxy ethanol havinga polyethoxy chain containing between about 15 and 35 mole equivalentsof ethylene oxide, (3) a condensation product of stcaramine or cocoamineand between about 2 and 4 mole equivalents of ethylene oxide, (4) acondensation product of coconut fatty acids and between about 4 and 6mole equivalents of of ethylene oxide, or (5) dilauryldimethyl ammoniumchloride.

14. A method of treating a permeable subterranean formation penetratedby a well which comprises injecting into the well a dispersion of up toabout 60 weight percent of oil-soluble, water-insoluble homogeneoussolid particles comprised of petroleum wax and polymer in an aqueoussolution containing 0.01 to 25 weight percent based upon the weight ofsaid solid particles of a surfactant selected from the group consistingof (l) a condensation product of laun'c acid or coconut fatty acids anddiethanolamine, (2) an octylphenoxy polyethoxy ethanol having apolyethoxy chain containing between about 15 and 35 mole equivalents ofethylene oxide, (3) a condensation product of stearamine or cocoamineand between about 2 and 4 mole equivalents of ethylene oxide, (4) acondensation product of coconut fatty acids and between about 4 and 6mole equivalents of ethylene oxide, or (5) dilauryldimethyl ammoniumchloride.

15. The method defined in claim 14 wherein said surfactant is acondensation product of coconut fatty acids and between about 4 and 6mole equivalents of ethylene oxide.

lti. A low loss fluid composition comprising in admixture (1) an aqueousliquid, (2) from 0.1 to 60 weight percent of oilsoluble, water-insolublehomogeneous solid particles having a means diameter of from aboutone-half inch to about 1 micron and comprised of petroleum wax, and (3)a surfactant in an amount of from about 0.0005 to 0.25 parts per part ofsolid particles and selected from the group consisting of nonionicsurface active ethers and thioethers having an HLB factor between about8.5 and 19.5, nonionic surface-active esters having an HLB factorbetween about 10 and 14.5, nonionic surface-active amides having an HLBfactor between about 7 and 10.5, nonionic surface-active amines havingan HLB factor between about 4 and 10, anionic surface-active sulfonateshaving an AFL factor between 7 and 12.5, surfaceactive organo-sulfateshaving an AFL factor between about 5.5 and 7,5, surface-activeorgano-phosphates having an AFL factor between about 12 and 39, andcationic surface-active agents having a CFL factor between about 19 and38.

17. The composition defined in ciaim'iiiTvhfriidilsoluble,water-insoluble solid particles are comprised of a solid solution ofpetroleum wax and polymer.

18. The composition defined in claim 17 wherein said polymer is selectedfrom the group consisting of 1) addition polymers of an olefin havingbetween 2 and 4 carbon atoms, 2) copolymers of an olefin having between2 and 4 carbon atoms and an alkyl acrylate containing not more than 4carbon atoms in the alkyl group, (3) copolymers of an olefin havingbetween 2 and 4 carbon atoms and an ester formed by the reaction ofbutenic acid and an alcohol having no more than 4 carbon atoms, and (4)co olymers of olefins having between 2 and 4 carbons atoms an an esterformed by the reaction of acetic acid and an unsaturated alcohol havingno more than 4 carbon atoms.

19. The composition defined in claim 17 wherein said polymer is selectedfrom the group consisting of polyethylene, polypropylene, copolymerethylene and methyl methacrylate, copolymer ethylene and vinyl acetate,and copolymer ethylene and ethyl acrylate.

20. The composition defined in claim 16 wherein said aqueous liquid isselected from the group consisting of (1) water, 2) brine, (3) aqueousacid solutions, and 4) aqueous caustic solutions.

21. The composition defined in claim 16 wherein said surfactant is (l) acondensation product of lauric acid or coconut fatty acids anddiethanolamine, (2) an octylphenoxy polyethoxy ethanol having apolyethoxy chain containing between about 15 and 35 mole equivalents ofethylene oxide,

(3) a condensation product of stearamine or cocoamine and between about2 and 4 mole equivalents of ethylene oxide, (4) a condensation productof coconut fatty acids and between about 4 and 6 mole equivalents ofethylene oxide, or dilauryldimethyl ammonium chloride.

22. A low loss fluid composition comprising a dispersion of up to about60 weight percent of oil-soluble, water-insoluble solid particlescomprised of a homogenous solid solution of petroleum wax and a polymerselected from the group consisting of polyethylene, polypropylene,copolymer ethylene and methyl methacrylate, copolymer ethylene and vinylacetate, and copolymer ethylene and ethyl acrylate in an aqueoussolution containing 0.01 to 25 weight percent based upon the weight ofsaid solid particles of a surfactant selected from the group consistingof l) a condensation product of lauric acid or coconut fatty acids anddiethanolamine, (2) octylphenoxy polyethoxy ethanol having a polyethoxychain containing between about 15 and 35 mole equivalents of ethyleneoxide, (3) a condensation product of stearamine or cocoamine and betweenabout 2 and 4 mole equivalents of ethylene oxide, (4) a condensationproduct of coconut fatty acids and betwee about 4 and 6 mole equivalentsof ethylene oxide, or (5) dilauryldimethyl ammonium chloride.

23. The composition defined in claim 22 wherein said surfactant is acondensation product of coconut fatty acids and between about 4 6 moleequivalents of ethylene oxide.

2. The method defined in claim 1 wherein said oil-soluble,water-insoluble solid particles are comprised of a solid solution ofpetroleum wax and polymer.
 3. The method defined in claim 2 wherein saidpolymer is selected from the group consisting of (1) addition polymersof an olefin having between 2 and 4 carbon atoms, (2) copolymers of anolefin having between 2 and 4 carbon atoms and an alkyl acrylatecontaining not more than 4 carbon atoms in the alkyl group, (3)copolymers of an olefin having between 2 and 4 carbon atoms and an esterformed by the reaction of butenic acid and an alcohol having no morethan 4 carbon atoms, and (4) copolymers of olefins having between 2 and4 carbon atoms and an ester formed by the reaction of acetic acid and anunsaturated alcohol having no more than 4 carbon atoms.
 4. The methoddefined in claim 2 wherein said polymer is selected from the groupconsisting of polyethylene, polypropylene, copolymer ethylene and methylmethacrylate, copolymer ethylene and vinyl acetate, and copolymerethylene and ethyl acrylate.
 5. The method defined in claim 2 whereinsaid petroleum wax is a paraffin wax.
 6. The method defined in claim 1wherein said aqueous liquid is selected from the group consisting of (1)water, (2) brine, (3) aqueous acid solutions, and (4) aqueous causticsolutions.
 7. The method defined in claim 1 wherein said surfactant is(1) a condensation product of lauric or coconut fatty acids anddiethanolamine, (a) an octlyphenoxy polyethoxy ethanol having apolyethoxy chain containing between about 15 and 35 mole equivalents ofethylene oxide, (3) a condensation product of stearamine of cocoamineand between about 2 and 4 mole equivalents of ethylene oxide, (4) acondensation product of coconut fatty acids and between about 4 and 6mole equivalents of ethylene oxide, or (5) dilauryldimethyl ammoniumchloride.
 8. A method of completing a well drilled into a permeablesubterranean formation which comprises circulating a low loss fluid fromthe formation surface to the drilling zone in said formation during thedrilling operation and returning to the surface at least a portion ofsaid fluid, said low loss fluid comprising a dispersion of oil-soluble,water-insoluble homogeneous solid particles comprised of petroleum waxin an aqueous liquid containing a surfactant selected from table
 1. 9.The method defined in claim 8 wherein said solid particles are comprisedof a soliD solution of petroleum wax and polymer.
 10. The method definedin claim 9 wherein said surfactant is (1) a condensation product oflauric acid or coconut fatty acids and diethanolamine, (2) anoctylphenoxy polyethoxy ethanol having a polyethoxy chain containingbetween about 15 and 35 mole equivalents of ethylene oxide, (3) acondensation product of stearamine or cocoamine and between about 2 and4 mole equivalents of ethylene oxide, (4) a condensation product ofcoconut fatty acids and between about 4 and 6 mole equivalents ofethylene oxide, or (5) dilauryldimethyl ammonium chloride.
 11. A methodof fracturing a permeable subterranean formation penetrated by a wellwhich comprises injecting a low loss fluid into said well and intocontact with said formation at a pressure and volume flow ratesufficient to fracture said formation, said low loss fluid comprising adispersion of oil-soluble, water insoluble, homogeneous solid particlescomprised of petroleum wax in an aqueous liquid containing a surfactantselected from table
 12. The method defined in claim 11 wherein saidsolid particles are comprised of a solid solution of petroleum wax andpolymer.
 13. The method defined in claim 11 wherein said surfactant is(1) a condensation product of lauric acid or coconut fatty acids anddiethanolamine, (2) an octylphenoxy polyethoxy ethanol having apolyethoxy chain containing between about 15 and 35 mole equivalents ofethylene oxide, (3) a condensation product of stearamine or cocoamineand between about 2 and 4 mole equivalents of ethylene oxide, (4) acondensation product of coconut fatty acids and between about 4 and 6mole equivalents of of ethylene oxide, or (5) dilauryldimethyl ammoniumchloride.
 14. A method of treating a permeable subterranean formationpenetrated by a well which comprises injecting into the well adispersion of up to about 60 weight percent of oil-soluble,water-insoluble homogeneous solid particles comprised of petroleum waxand polymer in an aqueous solution containing 0.01 to 25 weight percentbased upon the weight of said solid particles of a surfactant selectedfrom the group consisting of (1) a condensation product of lauric acidor coconut fatty acids and diethanolamine, (2) an octylphenoxypolyethoxy ethanol having a polyethoxy chain containing between about 15and 35 mole equivalents of ethylene oxide, (3) a condensation product ofstearamine or cocoamine and between about 2 and 4 mole equivalents ofethylene oxide, (4) a condensation product of coconut fatty acids andbetween about 4 and 6 mole equivalents of ethylene oxide, or (5)dilauryldimethyl ammonium chloride.
 15. The method defined in claim 14wherein said surfactant is a condensation product of coconut fatty acidsand between about 4 and 6 mole equivalents of ethylene oxide.
 16. A lowloss fluid composition comprising in admixture (1) an aqueous liquid,(2) from 0.1 to 60 weight percent of oil-soluble, water-insolublehomogeneous solid particles having a means diameter of from aboutone-half inch to about 1 micron and comprised of petroleum wax, and (3)a surfactant in an amount of from about 0.0005 to 0.25 parts per part ofsolid particles and selected from the group consisting of nonionicsurface active ethers and thioethers having an HLB factor between about8.5 and 19.5, nonionic surface-active esters having an HLB factorbetween about 10 and 14.5, nonionic surface-active amides having an HLBfactor between about 7 and 10.5, nonionic surface-active amines havingan HLB factor between about 4 and 10, anionic surface-active sulfonateshaving an AFL factor between 7 and 12.5, surface-active organo-suLfateshaving an AFL factor between about 5.5 and 7.5, surface-activeorgano-phosphates having an AFL factor between about 12 and 39, andcationic surface-active agents having a CFL factor between about 19 and38.
 17. The composition defined in claim 16 wherein said oil-soluble,water-insoluble solid particles are comprised of a solid solution ofpetroleum wax and polymer.
 18. The composition defined in claim 17wherein said polymer is selected from the group consisting of (1)addition polymers of an olefin having between 2 and 4 carbon atoms, (2)copolymers of an olefin having between 2 and 4 carbon atoms and an alkylacrylate containing not more than 4 carbon atoms in the alkyl group, (3)copolymers of an olefin having between 2 and 4 carbon atoms and an esterformed by the reaction of butenic acid and an alcohol having no morethan 4 carbon atoms, and (4) copolymers of olefins having between 2 and4 carbons atoms and an ester formed by the reaction of acetic acid andan unsaturated alcohol having no more than 4 carbon atoms.
 19. Thecomposition defined in claim 17 wherein said polymer is selected fromthe group consisting of polyethylene, polypropylene, copolymer ethyleneand methyl methacrylate, copolymer ethylene and vinyl acetate, andcopolymer ethylene and ethyl acrylate.
 20. The composition defined inclaim 16 wherein said aqueous liquid is selected from the groupconsisting of (1) water, (2) brine, (3) aqueous acid solutions, and (4)aqueous caustic solutions.
 21. The composition defined in claim 16wherein said surfactant is (1) a condensation product of lauric acid orcoconut fatty acids and diethanolamine, (2) an octylphenoxy polyethoxyethanol having a polyethoxy chain containing between about 15 and 35mole equivalents of ethylene oxide, (3) a condensation product ofstearamine or cocoamine and between about 2 and 4 mole equivalents ofethylene oxide, (4) a condensation product of coconut fatty acids andbetween about 4 and 6 mole equivalents of ethylene oxide, or (5)dilauryldimethyl ammonium chloride.
 22. A low loss fluid compositioncomprising a dispersion of up to about 60 weight percent of oil-soluble,water-insoluble solid particles comprised of a homogenous solid solutionof petroleum wax and a polymer selected from the group consisting ofpolyethylene, polypropylene, copolymer ethylene and methyl methacrylate,copolymer ethylene and vinyl acetate, and copolymer ethylene and ethylacrylate in an aqueous solution containing 0.01 to 25 weight percentbased upon the weight of said solid particles of a surfactant selectedfrom the group consisting of (1) a condensation product of lauric acidor coconut fatty acids and diethanolamine, (2) an octylphenoxypolyethoxy ethanol having a polyethoxy chain containing between about 15and 35 mole equivalents of ethylene oxide, (3) a condensation product ofstearamine or cocoamine and between about 2 and 4 mole equivalents ofethylene oxide, (4) a condensation product of coconut fatty acids andbetween about 4 and 6 mole equivalents of ethylene oxide, or (5)dilauryldimethyl ammonium chloride.
 23. The composition defined in claim22 wherein said surfactant is a condensation product of coconut fattyacids and between about 4 6 mole equivalents of ethylene oxide. 38.